<template>
  <div class="index" v-loading.fullscreen.lock="fullscreenLoading" element-loading-text="拼命加载中...">
    <a id="downlink"></a>
    <el-row>
        文件名：<input v-model="fileName" style="height:30px">
        <el-button type="primary" class="button" @click="downloadFile(excelData)">导出</el-button>
    </el-row>  
  </div>
</template>

<script>
  var XLSX = require('xlsx')
  export default {
    name: 'excel-export',
    props:{
        excelData: {
            type: Array,
            required: true
        }
    },
    data () {
      return {
        fullscreenLoading: false, // 加载中
        outFile: '',  // 导出文件el
       fileName: "请输入文件名"
      }
    },
    mounted () {
      this.outFile = document.getElementById('downlink')
    },
    methods: {
      downloadFile: function (rs) { // 按钮导出
        console.log(rs)
        let data = [{}]
        for (let k in rs[0]) {
          data[0][k] = k
        }
        data = data.concat(rs)
        this.downloadExl(data, this.fileName)
      },
     
      downloadExl: function (json, downName, type) {  // 导出到excel
        let keyMap = [] // 获取键
        for (let k in json[0]) {
          keyMap.push(k)
        }
        let tmpdata = [] // 用来保存转换好的json
        json.map((v, i) => keyMap.map((k, j) => Object.assign({}, {
          v: v[k],
          position: (j > 25 ? this.getCharCol(j) : String.fromCharCode(65 + j)) + (i + 1)
        }))).reduce((prev, next) => prev.concat(next)).forEach(function (v) {
          tmpdata[v.position] = {
            v: v.v
          }
        })
        let outputPos = Object.keys(tmpdata)  // 设置区域,比如表格从A1到D10
        let tmpWB = {
          SheetNames: ['mySheet'], // 保存的表标题
          Sheets: {
            'mySheet': Object.assign({},
              tmpdata, // 内容
              {
                '!ref': outputPos[0] + ':' + outputPos[outputPos.length - 1] // 设置填充区域
              })
          }
        }
        let tmpDown = new Blob([this.s2ab(XLSX.write(tmpWB,
          {bookType: (type === undefined ? 'xlsx' : type), bookSST: false, type: 'binary'} // 这里的数据是用来定义导出的格式类型
        ))], {
          type: ''
        })  // 创建二进制对象写入转换好的字节流
        var href = URL.createObjectURL(tmpDown)  // 创建对象超链接
        this.outFile.download = downName + '.xlsx'  // 下载名称
        this.outFile.href = href  // 绑定a标签
        this.outFile.click()  // 模拟点击实现下载
        setTimeout(function () {  // 延时释放
          URL.revokeObjectURL(tmpDown) // 用URL.revokeObjectURL()来释放这个object URL
        }, 100)
      },
      s2ab: function (s) { // 字符串转字符流
        var buf = new ArrayBuffer(s.length)
        var view = new Uint8Array(buf)
        for (var i = 0; i !== s.length; ++i) {
          view[i] = s.charCodeAt(i) & 0xFF
        }
        return buf
      },
      getCharCol: function (n) { // 将指定的自然数转换为26进制表示。映射关系：[0-25] -> [A-Z]。
        let s = ''
        let m = 0
        while (n > 0) {
          m = n % 26 + 1
          s = String.fromCharCode(m + 64) + s
          n = (n - m) / 26
        }
        return s
      },
      fixdata: function (data) {  // 文件流转BinaryString
        var o = ''
        var l = 0
        var w = 10240
        for (; l < data.byteLength / w; ++l) {
          o += String.fromCharCode.apply(null, new Uint8Array(data.slice(l * w, l * w + w)))
        }
        o += String.fromCharCode.apply(null, new Uint8Array(data.slice(l * w)))
        return o
      }
    }
  }
</script>

<!-- Add "scoped" attribute to limit CSS to this component only -->
<style>
  .el-table th>.cell {
    text-align: center;
  }
  .button {
    margin-bottom: 20px;
  }
</style>
